The Science Verification of FLAMES FRANCESCA PRIMAS, User Support Group, ESO

After a new VLT instrument has been sition of UVES and GIRAFFE observa- munity at large) and the proposed ex- commissioned and thoroughly tested1, a tions. ploitation of the instrument capabilities: series of scientific and technical check- The FLAMES Dry Runs took place ups are scheduled in order to test the successfully between the end of • The Chemical Signature of Different front-to-end operations chain before the January and the beginning of February Stellar Populations in the LMC: al- official start of regular operations. (Jan 24 – Feb 03, 2003). Nine science though it is considered an intermediate- Technically speaking, these are the so- programmes, proposed and assembled age galaxy, the LMC is characterised by called Dry Runs, part of which are usu- by the FLAMES SV Team (which in- a large range of stellar ages, from a ally devoted to the Science Verification cluded the VLT Programme Scientist, genuine old to a prominent young pop- (SV for short) of that specific instru- the Instrument PI, the Paranal ulation. The main goal of this project ment. Instrument Scientist, the User Support was to investigate further its metal en- A Science Verification programme in- Astronomer, members of the FLAMES richment history by measuring the cludes a set of typical scientific obser- Commissioning and Science Advisory abundances of several elements for a vations with the aim of verifying and Teams and representatives of the statistically significant sample of Red demonstrating to the community the ca- FLAMES Consortia), were executed. Giant Branch stars (17 < Vmag < 18). pabilities of a new instrument in the op- More than 5200 spectra were collected Two complementary projects were com- erational framework of the VLT Paranal during the ten observing nights, and bined: (1) the first spectroscopic metal- Observatory. Though manifold, its goals publicly released on March 3, exactly licity determination of the LMC Clump to can be summarised in two main points: one month after the last observing verify its influence (if any) on the intrin- from the scientific point of view, by night. This one-month time lag was nec- sic luminosity of the stars (by allocating demonstrating the scientific potential of essary to visually inspect the quality of 1/4 of the Medusa fibres to Clump the new instrument, these observations the frames (both raw and reduced), to stars); (2) the chemical analysis of LMC will provide ESO users with first sci- make the correct association between Long Period Variables in order to inves- ence-grade data, thus fostering an ear- raw and calibration frames to be distrib- tigate the connection (if any) among ly scientific return. From the technical uted, and to prepare a detailed set of their chemical composition, pulsation point of view, by testing the whole oper- summaries and technical explanations. mode, and evolutionary phase (the ational system (from the preparation of Any user from one of the ESO Member UVES fibres were used for this pur- the observations to their execution and States and with an active registration pose). Figure 1 shows the H-α region analysis), it will provide important feed- to the ESO/ST-ECF Archive (see for one RGB, one Clump, and one LPV back to the Instrument Operation http://archive.eso.org/register/new for star. Teams (both in Paranal and in more information), can download the Garching), to the Instrument Division, FLAMES SV datasets, whose scientific • Massive Kinematic Study of and to the Data Flow groups. More de- justifications are briefly described be- NGC 5128 using its Planetary tails about the concept(s) behind a low. The interested reader is reminded Nebulae and Globular Clusters as Science Verification can be found in the that a wealth of details (such as colour- Test Probes: planetary nebulae (PN) “Science Verification Policy and magnitude diagrams - to check which are emission line objects, the systemic Procedures” document (available at targets were observed, Field Charts velocities of which can be probed using http://www.eso.org/science/vltsv/). and README files - two of the main the brightest emission lines (see user requirements) are available Figure 2). The 785 PN found and cata- Science Goals and Achievements from the FLAMES SV web page logued by Hui et al. (1993), over a large (http://www.eso.org/science/vltsv). The area (4046 arcmin, EWxNS) of The Fibre Large Array Multi-Element following SV programmes were select- NGC 5128 (Centaurus A) were targeted Spectrograph (FLAMES) is the new ed based on their scientific weight (they in order to verify the initial findings that multi-object, intermediate- and high- must be interesting for the ESO com- PN kinematics trace a triaxial potential, resolution spectrograph of the VLT (Pasquini et al. 2002). Mounted at the Nasmyth A platform of Kueyen (Unit Telescope #2), FLAMES can access targets over a large corrected field of view (25 arcmin diameter). It consists of three main components: a Fibre Positioner (OzPoz) hosting two plates (while one plate is observing, the other is positioning the fibres for the next ob- servation); a link to the Red Arm of UVES (the high-resolution Ultraviolet and Visible Echelle Spectrograph) via 8 single fibres of 1 arcsec entrance aper- Figure 1: The H-α ture; a medium-high resolution optical region as observed spectrograph, GIRAFFE, equipped with with Medusa and three types of feeding fibre systems: UVES (top spec- 130 MEDUSA fibres, 15 deployable in- trum) in three stars tegral field units (IFU), and 1 large, fixed representative of integral field unit (ARGUS). A special the different stellar Observing Software (OS) coordinates populations probed the operation of the different subsys- in the Large tems, also allowing simultaneous acqui- Magellanic Cloud. 1Please note that all commissioning data are now available from http://www.eso.org/science/flames_comm/ 3 Figure 2: H-β and two [O III] lines in emission (the 495.9 and 500.7 nm), as detected in one of the planetary nebula observed with one Medusa fibre, at low resolution. More than 500 PN were observed in total. Figure 3: Two mass-loss diagnostics: the Ca H,K and the NaD lines, as observed in two different RGB stars of NGC 2808. with the mass-to-light ratio increasing •Elemental Abundances in NGC 2243: • Probing Activity and Angular Mo- with radius (thus suggesting the pres- a complete chemical analysis of sub-gi- mentum Evolution of Low-Mass ence of a dark matter halo). Some ant stars and membership information Members of the Orion Nebular MEDUSA and all UVES fibres were al- for the fainter, turn-off stars in this open, Cluster: surface rotation is a key ob- located to the brightest globular clusters metal-poor, intermediate-age (~ 2 Gyr) servational parameter for stellar evolu- of this giant elliptical galaxy in order to cluster were the main goals of the pro- tion, being tightly linked to the internal compare their kinematics and to derive gramme, which used two contiguous angular momentum transport, hence to their metallicity. (hence slightly overlapping) high-reso- mass loss. The main goal of this pro- lution Medusa set-ups (Figure 4). The gramme was to determine the v sini dis- • Mass Loss in Red Giant Stars of main scientific interest of this cluster lies tribution for a large number (120 tar- the Globular Cluster NGC 2808: in two aspects: its metallicity, which is gets, selected from the low-resolution about 100 stars of the Red Giant comparable to the halo cluster 47 survey of Hillenbrand 1997) of low- Branch, in the magnitude interval Tucanae, and its age which is instead mass (0.2–0.06 M), relatively cold V=13.2–16.5 mag, within a radius of remarkably smaller (47 Tuc formed (logTeff < 3.5), M5–M7 type stars in the about 7 arcmin from the cluster centre, some 10–12 Gyrs earlier). A direct Orion Nebular Cluster (~1 Myr old, were targeted, with the aim of measur- abundance comparison between these 430 pc away), for which only little infor- ing shifts of the CaII-K3, NaD and H-α two clusters (47 Tucanae has been ex- mation is available. Recent observa- core line profiles that are major diag- tensively observed with UVES in the tions in Orion have shown that while the nostics of mass outflow, hence mass past) will shed light not only on their majority of low-mass pre-main se- loss. In order to observe the Ca H and chemical history, but also on the forma- quence stars are rotating at rates ap- K lines, this programme made use of tion and evolution of our own Galaxy. proaching 30% of breakup, late-type one of the bluest settings available on FLAMES, HR#2, which covers the spectral range between 385 and 405 nm (see Figure 3). The brightest stars of the cluster were observed si- multaneously with UVES, to obtain a larger spectral coverage (480–680 nm) for chemical abundance purposes.

• Geometric Distances of the Galactic Globular Cluster NGC 2808: the main idea behind this science case was to observe a very large number of stars (1000), and derive their radial velocities, in order to obtain the first determination of the cluster geometric distance (with an uncertainty of 2–3%, i.e. an age with an error less than 1 Gyr) via a direct comparison of the radial velocities to the (already available) proper motions. One GIRAFFE set-up (HR#5), together with the simultaneous allocation of UVES-fibres, was also used to obtain spectra of horizontal branch stars, thus increasing by one order of magnitude the size of the present sample. Figure 4: The same NGC 2243 sub-giant star, as observed in two contiguous high resolu- tion Medusa settings: the total spectral coverage is from 638 to 697 nm.

4 stars in older clusters appear to be slow Figure 5: The efficiency rotators (e.g. Stassun et al. 1999, and rate achieved during the Queloz et al. 1998, respectively). FLAMES Dry Runs: “Science” means the • Kinematics of Distant Galaxies from time spent on target, with FLAMES-GIRAFFE IFU Mode: the respect to the “astronom- main goals of this programme were a) ical” length of each night, to derive, from spatially-resolved spec- whereas the values on troscopy and HST images, velocity the “Science+Acquisition” fields and rotation curves of galaxies curve also include the with emission lines at moderately high time spent on acquiring redshift; b) to kinematically map merg- the target fields and the ing systems, in order to quantify the set-up of the instrument. number of perturbed galaxies and the merging rate; c) to study the evolution of the Tully-Fisher relation in order to com- persion and infer some constraint on ticular phase during which a user, with plement the study of the mass and M/L the ellipsoid of velocity dispersions in advice (if needed) from a pre-assigned functions. The chosen target was the the central part of the galaxy NGC 3585. support astronomer, submits a set of well-known cluster of galaxies, MS This programme made use of one high- Observation Blocks (i.e. logical units of 1054-03, at redshift z = 0.83. FLAMES and one low-resolution setting (HR#12 exposures to be executed at the tele- was used in combined mode: the 15 and LR#05, respectively) using the scope to obtain a coherent set of data) Integral Field Units were mainly allocat- same fibre configuration. and detailed information on how her/his ed to late-type galaxies Sc-Sd, merger own programme should be carried out. systems and post-starburst spiral galax- The time spent on each of these pro- This process requires the availability of ies, whereas UVES fibres were devoted grammes and their completion rate (giv- software tools, documentation, and a to four elliptical galaxies and one merg- en in percentage), together with the list of generic and instrument-depend- ing system, all brighter than 21 mag in chosen instrument modes and set-ups, ent requirements that need to be ful- I-band. are summarised in Table 1. filled. In the case of a SV Phase 2, this • Dark and Stellar Mass in Late-type A Success process must be anomalous, by defini- Dwarfs: even if the existence of dark tion: the instrument has not yet been re- matter in spiral galaxies is well estab- Three important factors are behind leased for official operations, and all lished, there are large uncertainties re- the success of the FLAMES SV : a sta- software tools, user documentation and garding its distribution inside the optical ble instrument, very cooperative atmos- user manuals are still in the final stages disc. The aim of this programme was to pheric conditions, and a set of well pre- of revision. These uncertainties clearly measure the (stellar) vertical velocity pared science observations. The com- require some flexibility on the side of the dispersion, from which one can directly bination of the first two points made it SV Team while preparing the observa- measure the product M/L × q0, where possible to achieve a very high efficien- tions (this is also why a SV Team main- M/L is the stellar mass-to-light ratio of cy over the entire window of the ob- ly includes people who have been al- the stars and q0 the thickness of the serving run, as shown in Figure 5, ready exposed to the instrument, during disc. Observationally, this requires high where the time spent on “science tar- its development, assembling, and com- spectral resolution: the selected target, gets” and normalised to the total num- missioning phases). NGC 1310, is less massive than the ber of hours available per night (as de- In the case of FLAMES SV, Phase 2 Milky Way; it rotates at 110 km/s, thus fined by the astronomical twilights) is took place over the Christmas break. All requiring a velocity resolution of the or- shown for the entire run. On the third the required material was delivered to der of 10–20 km/s. The target was se- aspect, i.e. the preparation of the sci- ESO in mid January, then checked and lected to fulfil the following criteria: ence observations, a more extensive verified by the FLAMES user support preferably late-type, close to face-on, and detailed description is needed. astronomer, and made available to the and not barred. The observations were In the very early organisational phas- team of night- and day-time astro- carried out with 5 IFU placed at a radius es of the FLAMES SV, it was decided to nomers present on Paranal for the exe- of 1 scale length and the remaining 10 try and implement a real (although for cution of the observations. During this at a radius of 2 scale lengths. many aspects anomalous) Phase 2. phase, a thorough assessment of the With this term, familiar to all those as- quality of the available tools and manu- • Dynamical Study of Elliptical tronomers who have had their observa- als was made, which proved to be very Galaxies: the scientific objective was tions carried out in “Service Mode” (cf useful for the official Period 71 Phase 2, to accurately determine the velocity dis- Silva 2001), we usually identify that par- that started at the beginning of February

Table 1: FLAMES SV Science Programmes Programme Instr. Mode Instr. Set-Up Invested Time Completion Rate hours %

NGC 5128: PN and GC Medusa+UVES LR3+R580 7 75 LMC: Stellar Populations Medusa+UVES HR13,14+R580,R860 21 76 NGC 2808: Mass loss Medusa+UVES HR2,11,14+R520 4 100 NGC 2808: Geometric Distance Medusa+UVES HR5,9+R520 7 100 NGC 2243: Abundances Medusa+UVES HR14,15+R580,R860 4 100 ONC: Low-mass Stars Medusa HR14,15 5 62 MS 1054-03: Kinematics IFU+UVES LR6+R860 9 75 NGC 1310: Dark and Stellar Mass IFU LR4 5.5 100 NGC 3585: Dynamics IFU HR12,LR5 5 100

5 packages to the users), and the der to have a quick-look at the spectra Instrument Division in Garching (which quality, while observing. All these has been responsible for developing, “quick-look” reduced spectra were pub- building and commissioning the instru- licly distributed together with the raw ment). science and calibration frames, so that The FLAMES SV has been a very the entire ESO community could bene- positive experience, also from the oper- fit equally from this set of observations. ational point of view. The lessons Those observations for which no quick- learned during the implementation, exe- look spectrum could be extracted, were cution, and quality assessment of these promptly made available to the Data FLAMES observations have proven to Flow System group, in order to test the be very valuable, for the instrument robustness and repeatability of the support teams and also for the first pipeline-reduction framework against FLAMES users (i.e. those with FLAMES different sets of science data. programmes approved for P71), who benefited from more robust and user- The End of the Adventure friendly instrument-related tools. The first positive outcome came from In retrospect, as the FLAMES SV co- the (SV) Phase 2 exercise, which ordinator, I must say that the very posi- Figure 6: The centring of the reference stars turned out to be a thorough testing of tive and successful experience of the on the Fibre Acquisition Coherence Bundles, the FLAMES Fibre Positioner Obser- FLAMES Science Verification Dry Runs as seen at the telescope console. vation Support Software (FPOSS) on has undoubtedly resulted from the hard real and different science cases (for work of several people, who deserve to (see next section). Passing the Phase 2 which the user wants to allocate one be properly acknowledged. First of all, verification usually offers the user and specific group of fibres to one specific the FLAMES SV Team members (led by the operations team some confidence group of targets). This revealed a series A. Renzini, and including M. R. Cioni, N. that the execution of a given pro- of shortcomings in the FPOSS tool, Cretton, A. Kaufer, C. Melo, L. Pasquini, gramme should go smoothly. However, which was revised and further tested as M. Rejkuba, M. Romaniello J. Walsh, M. should the user have mistyped some SV observations were taking place. Zoccali, and myself - at ESO - and A. crucial information (like the target coor- Among the technical problems encoun- Blecha, C. Cacciari, V. Cayatte, and V. dinates), this will be detected only at the tered at the telescope, the most recur- Hill, as representatives of the FLAMES telescope. Because of the multiplex ca- ring one was the “non-validity” of some Consortia) for having proposed and de- pability of FLAMES, target coordinates UVES+Medusa fibre configurations, veloped the science cases in a very are even more important for successful which had instead been validated by flexible and timely manner. The Paranal observations. One needs very precise FPOSS during Phase 2. The need for FLAMES SV Team (A. Kaufer, J. relative coordinates of several hun- solving this type of problem in real-time Smoker, R. Schmutzer, C. Melo, M. dreds of targets in the field to be ob- gave us a deeper understanding of how Rejkuba and myself) played a funda- served - technically speaking, one fibre-collisions were handled and treat- mental role in securing an excellent set needs very accurate astrometry (< 0.3 ed, both at FPOSS and OzPoz levels. A of first-grade science data (considering arcsec). As FLAMES does not have a quick recovery procedure at night time all the debugging, fixes and revisions pre-imaging option, there is only one (by “manually” de-allocating the collid- implemented in real time at the tele- parameter/tool available to evaluate the ing fibres) was then followed by the de- scope). One of the main strengths of quality of the astrometry: Figure 6 bugging phase at software level during this group was its very positive, friendly, shows an image of the Field Acquisition day-time operations, perfectly in time to and constructive team spirit. Among the Coherence Bundles (as seen at the tel- test the newly revised version during ESO Fellows, the extra workloads un- escope console) for one set of observa- the following night. dertaken at different stages of the tions that were carried out during the As SV observations are carried out in FLAMES SV adventure by M. Rejkuba, FLAMES SV. These bundles (normally Service Mode, the presence or absence M. Zoccali, and N. Cretton need to be four, but at the time of the SV run the of difficulties during the execution of a recognised. Finally, the cooperation of- fourth one was not available) show how given programme (based on the infor- fered by the ESO/ST-ECF Science well centred the reference stars are, mation provided by the Principal Archive (in particular, B. Pirenne and N. which must be chosen in the same as- Investigator) gave us an idea of how Rainer) made it possible to release all trometric solution as the science tar- complete the preliminary list of user re- the data packages on a very com- gets. quirements (set up during the SV Phase pressed timescale. Thank you all! 2) was. Because of the presence at the Lessons Learned telescope of most of the persons in- Acknowledgements volved in the FLAMES operations, it As stated at the very beginning of this was possible to revise in real time all the The author would like to thank presentation, one of the main goals of a user-related documentation (e.g. User Pamela Bristow for a careful reading of Science Verification run is the important Manuals) and the software tools, like the manuscript. technical feedback that can be given to FPOSS, thus solving and implementing the teams directly involved in the front- all the “bugs and wishes” we had as- References to-end operations of that instrument, i.e. sembled after Phase 2, and to prepare the Paranal Science Operation team all FLAMES operations-related Web Hillenbrand, L. A., 1997, AJ, 113, 173 (responsible for its operations), the pages. Hui, X., Ford, H. C., Ciardullo, R., Jacoby, G. User Support Group (the operational-in- As the observations were being car- H., 1993, ApJS, 88, 423 terface between the users community ried out, we also tried to reduce all the Pasquini, L. et al., 2002, The Messenger, and the Observatory), the Data Flow frames in a semi-automatic way, with 110, 1-9 groups (i.e. those behind the develop- the reduction recipes available at that Queloz, D., Allain, S., Mermilliod, J.-C., ment of instrument-specific data-reduc- Bouvier, J., Mayor, M., 1998, A&A, 335, time. This was done on a best-effort ba- 183 tion recipes, the implementation of qual- sis, as it was a low priority item on the Silva, D., 2001, The Messenger, 105, 18-24 ity-control and monitoring checks, the FLAMES SV team “to-do” list. However, Stassun, K. G., Mathieu, R. D., Mazeh, T., archival and distribution of the data- it was decided to invest the effort in or- Vrba, F. J., 1999, AJ, 117, 2941

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